In a portable terminal such as a mobile phone, a product being excellent in not only thin and light weight structure but also rich in functionality is demanded in recent years. For example, the portable electronic device stated in Patent Reference 1 includes a first housing, a second housing with a display device on its front side, and a two-axial type hinge having two rotational shaft in a position being twisted to each other. Thus, by enabling the second housing to be rotationally moved in two directions, forms of applications of the portable terminal can be increased.
Moreover, as a portable terminal product, a product being rich in designing quality is demanded. For example, as shown in FIGS. 9A and 9B, in the foldable portable terminal device 100, by causing its housing 102 (hereinafter, may be referred to as a display housing) having a display device 101 to be thinner towards its end side, its design quality is enhanced. The portable terminal device 100 is made up of an operational housing 103, a display housing 102, and a hinge unit 104. The hinge unit 104 is constructed as a two-axial mechanism and the display housing 102 rotationally moves around the opening and closing axis Y along the width direction of the portable terminal device 100 and rotationally moves around the inverting axis X forward and backward along the longitudinal direction of the display housing 102.
By rotating the display housing 102 around the inverting axis X, as shown in FIG. 9A, there occurs a display inward directing state in which the portable terminal device 100 is closed and, as shown in FIG. 9B, there occurs a display outward state directing state in which the portable terminal device 100 is closed. Moreover, the display inward directing state represents the state in which a display housing front 102a forming a same surface as the display surface of the display device 101 faces the operational housing 103. The display outward directing state represents the state in which a display housing rear 102b on a rear side of the display housing front 102a faces the operational housing 103.